The invention relates to a process of fabricating an elongated glass body, particularly a preform for optical waveguides on the basis of SiO.sub.2, in which from powdery glass starting material a porous body is formed which is sintered to obtain the glass body.
One such process is known from U.S. Pat. No. 4,501,601. The forming of the porous body from the powdery glass starting material is carried out in this process by causing the powdery glass starting material to loosely run into a compression mold, with the loosely filled-in material then being compressed into the desired shape of the porous body This kind of fill-in procedure, which may also be referred to as a fill, results in only a relatively low density at the conclusion of the filling operation, especially in the case of powders of very fine distribution, so that a shape-keeping compression is rendered difficult. Moreover, the compression mold is only inhomogeneously filled in the course of this filling operation, because cavities are likely to result owing to bridge formations in the powder.
A similar process is known from the German Pat. No. DE-PS 32 40 355, in which the glass starting material in the form of granules is loosely piled up to form a bulk body, with this bulk body being stabilized in shape on its circumference during its pile up and then, by way of compression, being formed into a porous body. This process also has the disadvantage that only a slight density and cavities are likely to result in the bulk body from the piling up, by which a shape-keeping compression is rendered difficult.